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Question 1 of 3

A pharmacist weighed 240 milligrams of Codeine Sulphate on a balance with a sensitivity of 10 milligrams. What is the maximum potential error as a percentage of this weighing? Answer to 1 decimal place.
Type in your answer and PRESS ENTER.
%
The maximum error is 4.2%.

Percentage Error =              Error              x 100 %
Actual Measurement

The sensitivity of the balance is 10 milligrams so the weighing could be out by a maximum of 10 milligrams. Thus "Error" is 10 milligrams.

Percentage Error = 10 x 100 %
240
Percentage Error = 4.16 %
Percentage Error = 4.2 % to 1 dec pl

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Question 2 of 3

A pharmacist weighs 925 milligrams of Quinine Bisulphate on a balance. However, when the Quinine Bisulphate is then weighed on a highly accurate balance, the Quinine Bisulphate weighs 850 milligrams. What is the percentage error of the first weighing? Answer to 1 decimal place.
Type in your answer and PRESS ENTER.
%
The percentage error is 8.1%.
  1. Find the error in weighing.
    Error = First Weighing - Accurate Weighing
    Error = 925 - 850mg = 75mg
  2. Find the percentage error.

    Percentage Error =              Error              x 100 %
    Actual Measurement

    Percentage Error =75 x 100%
    925
    Percentage Error = 8.10%
    Percentage Error = 8.1% to 1 dec pl

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Question 3 of 3

A 10 ml conical dispensing measure weighs 47.345 grams. 5 ml of distilled water are measured in it and the combined weight of the dispensing measure and water is 52.165 grams. What is the deviation from 5 grams expressed as percentage error? (You know that 1 ml of water weighs 1 gram) Answer to 1 decimal place.
Type in your answer and PRESS ENTER.
%
The percentage error is 3.6 %.
  1. Find the measured weight of the 5 ml of water.
    Measured Weight = (Weight of Measure + Water) - Weight of Measure Measured Weight = 52.165 - 47.345g = 4.820g
  2. The true weight of 5 ml of water is 5 g.
  3. Find the error in the measurement of the water. Error = True Weight - Measure Weight Error = 5 - 4.820g = 0.180g
  4. Find the percentage error in weighing.
    Percentage Error =              Error              x 100 %
    Actual Measurement
    Percentage Error = 0.180 x 100%
    5
    Percentage Error = 3.60%
    Percentage Error = 3.6% to 1 dec pl

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